6 ideas
| 9987 | An aggregate in which order does not matter I call a 'set' [Bolzano] |
| Full Idea: An aggregate whose basic conception renders the arrangement of its members a matter of indifference, and whose permutation therefore produces no essential difference, I call a 'set'. | |
| From: Bernard Bolzano (Paradoxes of the Infinite [1846], §4), quoted by William W. Tait - Frege versus Cantor and Dedekind IX | |
| A reaction: The idea of 'sets' was emerging before Cantor formalised it, and clarified it by thinking about infinite sets. Nowadays we also have 'ordered' sets, which rather contradicts Bolzano, and we also expect the cardinality to be determinate. |
| 10856 | A truly infinite quantity does not need to be a variable [Bolzano] |
| Full Idea: A truly infinite quantity (for example, the length of a straight line, unbounded in either direction) does not by any means need to be a variable. | |
| From: Bernard Bolzano (Paradoxes of the Infinite [1846]), quoted by Brian Clegg - Infinity: Quest to Think the Unthinkable §10 | |
| A reaction: This is an important idea, followed up by Cantor, which relegated to the sidelines the view of infinity as simply something that could increase without limit. Personally I like the old view, but there is something mathematically stable about infinity. |
| 3583 | External objects are permanent possibilities of sensation [Mill] |
| Full Idea: External objects are permanent possibilities of sensation. | |
| From: John Stuart Mill (Examination of Sir Wm Hamilton's Philosophy [1865]), quoted by Michael Williams - Problems of Knowledge Ch.9 |
| 3537 | I judge others' feeling by analogy with my body and behaviour [Mill] |
| Full Idea: I conclude other humans have feelings like me because they have bodies like mine (which I know in my case to be antecedent to feelings), and because they exhibit acts and outwards signs which I know in my own case to be caused by feelings. | |
| From: John Stuart Mill (Examination of Sir Wm Hamilton's Philosophy [1865], p.243), quoted by Keith T. Maslin - Introduction to the Philosophy of Mind 8.2 | |
| A reaction: It is hard to see anything further that can be added to the 'other minds' question. Behaviour is highly relevant (imagine meeting a human who talked like a robot), but so are bodies (imagine a tin box that talked like Marilyn Monroe). |
| 1474 | Moral evil may be acceptable to God because it allows free will (even though we don't see why this is necessary) [Plantinga, by PG] |
| Full Idea: Moral evil may be acceptable to a benevolent God because it is the only way to allow genuine free will, which may have a supreme value in creation (even if we are unsure what it is). | |
| From: report of Alvin Plantinga (Free Will Defence [1965], Pref.) by PG - Db (ideas) |
| 1475 | It is logically possible that natural evil like earthquakes is caused by Satan [Plantinga, by PG] |
| Full Idea: Physical evil (e.g. earthquakes) may be attributable to a fallen angel (Satan), who is the enemy of God, and this is enough to retain the idea that God is omnipotent and benevolent, and yet evil exists. | |
| From: report of Alvin Plantinga (Free Will Defence [1965], III) by PG - Db (ideas) |